CT scan evaluation of tumor response to thermoradiation therapy

Objective: To investigate the value of CT scan to evaluate the tumor response to thermoradiation therapy. Methods: Combined ultrasound hyperthermia and radiotherapy was used in 134 patients with advanced malignancies, of whom 23 showing little change in mass size but obvious liquefaction and necrosis after treatment, were followed up with enhanced CT scan for 3-24 months. The effects were evaluated by percentage of low density area and level of enhancement in tumor on CT scan. The remaining 111 patients were evaluated by the WHO criteria. Results: In 111 patients evaluated by the WHO evaluation of tumor response, 32 showed CR and 79 PR + NC. In 23 patients evaluated by percentage of low density area on CT scan, 10 showed CR(>80% of low density area in tumor), 10 PR(50%-80%) and 3 NC(<50%). All the 10 CR patients evaluated by CT scan were stable and did not develop recurrence in 12-24 months after treatment. Three of 10 CR patients were punctured and 1 was resected for biopsy, with pathology showing coagulation necrosis without any tumor cells. Of the 10 PR patients evaluated by CT scan, the lesion of 8 recurred locally in 12 months. All the 3 NC patients by CT scan recurred locally in 6 months. There were no significant differences in the 1-year local control and 1-year overall survival rates between the 111 patients evaluated by the WHO criteria and 23 evaluated by CT scan (P>0.05). Conclusion: For tumor treated with hyperthermia plus radiotherapy, the response evaluation should be based on both the change in the mass size and the percentage of low density area in the tumor